The invention refers to a traveling crane with end plates located at the ends of a bridge girder, provided with boreholes for screws by means of which top girders provided with carrying wheels are attached to the bridge girder.
Such a traveling crane has been disclosed by French patent application specification No. 1 405 710, having plates welded in the top girder for reinforcement. Bushings are welded to the top girder to accommodate the carrying wheels. As the top girder is not manufactured to close tolerances as an individual part, and furthermore buckles when welding in the plates, a large precision tool is needed to mill the boreholes for the wheel bearings. Th same holds true also for finishing treatments of the end plate of the bridge girder, to which the top girder is attached for precise and aligned arrangement of the carrying wheels.
It is therefore the object of the invention to design a traveling crane so that the bridge girder and the end plates may be finished with minimum expenditure and simple means. This is achieved by surrounding the boreholes with recesses for receiving tubular sleeves or washers receiving the screws, whereby the bottoms of all such recess lie in a common reference plane and all of the tubular sleeves extend to the reference plane. Only the recesses and the tubular sleeves need be of precise dimensions, while the remaining parts may show some unevenness, since they do not touch on account of the tubular sleeves guaranteeing a clearance space between the end plates of the bridge girder and the top girder.
In a further development of the invention, the tubular sleeves may reach through boreholes in both walls of box-shaped top girders and may be attached by welding. In this case the tubular sleeves replace the plates which are otherwise often necessary. During welding of the tubular sleeves the top girder warps less than during the welding of the plates. No special skill is needed for welding the tubular sleeves, as they protrude beyond the walls of the top girder. Before welded to the top girder, the tubular sleeves are placed on an exact appliance, forming the reference plane for centric boreholes in the top girder, through which bolts reach later on to hold carrying wheel bearings in place. Recesses in the top girder may also form a reference plane.
The carrying wheel bearings are, in further development of the invention, made of bracket halves pressed into U-like forms and welded together at weld-on flanges touching one another. Support surfaces for roller bearings are pressed into the bracket walls. Next to the carrying wheel, downward extensions of the bracket walls form a derailment guard by protruding beyond the bottom of the top girder which is provided with a cut-out at the bottom just before its end. The derailment guard becomes effective after a possible wear of the rims.
To permit the drive axle of each motor driven carrying wheel to pass through the lateral wall of the top girder, a slot reaching up to its front end is provided whose upper limit ascends towards the front end. This ascending slot makes it possible to pull the carrying wheel bearing out of the top girder if it needs to be exchanged. To this end, the top girder is slightly raised at first, then the bolts are knocked out and the complete carrying wheel bearing is pulled to the front end and raised since the top girder forms a closed box profile at the front end, and the carrying wheel must be lifted over its lower wall.
When exchanging the carrying wheel, the entire carrying wheel bearing is exchanged since the pertaining parts are joined together in undetachable fashion. For this reason the axle has the shape of a truncated cone in the area of the carrying wheel and pressed into the matching borehole of the carrying wheel, after the parts have been coated with an adhesive over the entire area to be joined. As adhesive Loctite is especially recommended.
In further development of the invention, each carrying wheel may, at the front end of the top girder, be provided with a welded-in nut or with a threaded borehole for the retaining screw of a front plate, whereby the retaining screw may be imbedded in a bumper (cushion?) absorbing shocks from collisions.
Several examples of the invention are shown on the drawings and explained as follows: